Plasticizing and injection unit for use in an injection molding machine

Abstract

The plasticizing and injecting unit comprises at least one hydraulic advance-retract actuator that is provided with external screw threads, which are screwed into internal screw threads of a bore formed in a carrier and supply block. Means for locking the advance-retract actuator in the bore in that the interengaging screw threads are wedged against each other comprise a plurality of lock screws, which are parallel to the injection axis and disposed on a circle that surrounds the bore in which the actuator is received. The screws can be tightened to different degrees so that the carrier and supply block and the advance-retract actuator are biased in mutually opposite senses and any deviations from a coaxial arrangement of the interengaging screw threads can thus arbitrarily be changed in its magnitude and direction. As a result, the stresses which result in the overall structure from a deviation from a coaxial arrangement can be minimized by a simple manipulation.

I claim: 
     
       1. In a plasticizing and injecting unit for use in an injection molding machine, comprising a carrier and supply block, which has a first bore having a horizontal center line, which defines an injection axis, and at least one second bore, which is formed with internal screw threads, has an axis that is parallel to and spaced from said injection axis,   a plasticizing cylinder, which is detachably mounted in said first bore,   a cylindrical hydraulic advance-retract actuator, which has an axis and extends in said second bore and has external screw threads interengaging with said internal screw threads so as to permit said actuator to assume relative to said second bore a non-coaxial position involving an angular misalignment between the axes of said actuator and of said second bore, and   locking means comprising screw means, which are screwable to wedge said internal and external screw threads against each other to fix said actuator in said carrier and supply block,   the improvement residing in that   Said screw means comprise a plurality of lock screws, which extend substantially parallel to said injection axis and are spaced apart approximately on a circle surrounding said axis of said second bore and are tightenable to selectively bias said carrier and supply block and said actuator in mutually opposite senses so that said angular misalignment can be controlled in its magnitude and direction.   
     
     
       2. The improvement set forth in claim 1, as applied to a plasticizing and injecting unit in which said actuator is arranged to be subjected to a misaligning moment tending to move said actuator to said non-coaxial position. 
     
     
       3. The improvement set forth in claim 1 as applied to a plasticizing and injecting unit in which said carrier and supply block has a plurality of second bores, each of which has internal screw threads and have respective axes which are parallel to and spaced around said injection axis and a plurality of said cylindrical hydraulic advance-retract actuators are provided, each of which extends in one of said second bores and is fixed to said carrier and supply block by said locking means, wherein said screw means comprise in association with each of said actuators a plurality of lock screws, which extend substantially parallel to said injection axis and are spaced apart approximately on a circle surrounding said axis of said second bore, containing said associated actuator and are selectively tightenable to selectively bias said carrier and supply block and the associated actuator in mutually opposite senses so that said angular misalignment can be controlled in its magnitude and direction.   
     
     
       4. The improvement set forth in claim 3 as applied to a plasticizing and injecting unit in which each of said actuators comprises a stationary piston and guide rod which is parallel to said injection axis, wherein each of said actuators comprises a cylinder that is formed with said external screw threads and slidably mounted on one of said piston and guide rods, and   each of said actuators comprises forward and rear end portions axially protruding from said carrier and supply block on opposite sides.   
     
     
       5. The improvement set forth in claim 4, wherein each of said cylinders has an end portion axially protruding from said carrier and supply block and formed with additional external screw threads,   said locking means comprise for each of said cylinders a tapped ring screwed on said additional external screw threads and   said plurality of screws associated with each of said actuators are screwed to said tapped ring associated with said actuator and have each an end portion which axially protrudes from said tapped ring toward said carrier and supply block and in engagement with said carrier and supply block.   
     
     
       6. The improvement set forth in claim 2 as applied to a plasticizing and injecting unit that comprises a plurality of stationary guide rods extending through respective ones of said second bores and a feed screw actuating bridge which is axially slidably mounted on two of said guide rods, which extend through two of said second bores, wherein each of said two second bores has a first portion, which is adjacent to said bridge and relatively small in diameter, and a second portion, which is remote from said bridge and relatively large in diameter and formed with said internal screw threads,   said carrier and supply block has internal flanges radially protruding into respective ones of said two second bores at that end of said second portion which is remote from said first portion,   one of said actuators extends in each of said two bores and comprises an injecting piston, which is slidably mounted on one of said two guide rods and is connected to said feed screw actuating bridge, and a cylinder, which is slidably mounted on said piston and has an end portion which is formed with said external screw threads and has an end face facing said internal flange, and   said plurality of lock screws associated with each of said two actuators are screwed into one of said internal flanges and have free ends engaging said end face of the associated cylinder.   
     
     
       7. The improvement set forth in claim 6, wherein each of said cylinders has opposite to said end face a second end face and is formed adjacent to said second end face with internal screw threads,   two cylinder covers are provided, each of which has external screw threads screwed into said internal screw threads of one of said cylinders and comprises a radial flange covering said second end face of said cylinder on a full circle and   each of said injecting pistons comprises a first portion, which is relatively large in diameter and axially protrudes from said carrier and supply block on the side thereof which is remote from said bridge, and a second portion, which is relatively small in diameter and extends through said cylinder cover.   
     
     
       8. The improvement set forth in claim 7, wherein each of said cylinders has an axis and each of said cylinder covers has an axis and is adapted to assume a non-coaxial position involving an angular misalignment between said axes of said cylinder and said radial flange, and   a plurality of lock screws disposed approximately on a circular line are screwed to each of said radial flanges and are selectively tightenable to lock said cylinder cover and to bias said cylinder cover and the associated cylinder in mutually opposite senses so that said angular misalignment of said axes of said cylinder and of said radial flange can arbitrarily be changed.   
     
     
       9. The improvement set forth in claim 1, wherein said actuator has an end portion axially protruding form said carrier and supply block and formed with additional external screw threads,   said locking means comprise a tapped ring screwed on said additional external screw threads, and   said plurality of screws are screwed to said tapped ring and have each an end portion which axially protrudes from said tapped ring toward said carrier and supply block and in engagement with said carrier and supply block.   
     
     
       10. The improvement set forth in claim 9, wherein said carrier and supply block has an end face facing said tapped ring and formed with an annular series of recesses and   said end portions of said screws engage said carrier and supply block in said recesses.